While indeed yes, TN is "better" for gaming, this mostly applies only to professional FPS gamers, who are willing to sacrifice in other areas, just to get the last milliseconds in pixel response times. For regular gamers who actually like image quality, the TN simply isn't worth the compromises. It's basically gaining 10% in ONE area, and losing 30% in ALL the others.
Also, if you're not going for 144Hz, then you lose half of the TN benefit, which was already small, to begin with. And if going for 144Hz, the cheapest 27" 144Hz TN is £280. If you add £20 more, you could get the
Acer XZ271Q for £300, which is quite similar, except it has a curved VA panel and FreeSync. Which in turn is something I would highly recommend, though. Just yesterday I got its big brother XZ321Q, and let me tell you: it's phenomenal (gonna have to make a review during the weekend).
As for the 27" and 1080p:
Whether 27" is too big for 1080p is an individual matter, depending on the user's eye sight and viewing distance. I just recently got a 32" 1080p screen (XZ321Q, like stated above), and overall, I think it's great. But personally, I actually find it a little too small. 1440p would have been a total disaster for me. Previously I had a 42" HDTV (1080p), which I found just right for a 1m viewing distance. Furthermore, with 1080p you'll get higher frame rates, or alternatively you can crank up the detail settings and anti-aliasing levels.
Anyway, if you want to keep the budget and 27", then there are these non-TN options, just to name a few:
Acer KA270HBID for £150 (pre-order)
Acer KA270H for £150 (this one is older, out of stock, not sure if there's any major difference to the above model...?)
BenQ GW2760HS for £180 (I've recommended this in the past, never heard a bad word back -- but indeed, this model is from 2013, so it's getting old)
Samsung C27F390 for £210 (similar to the XZ271Q, but only 60Hz)
Conclusion:
If you can stretch the budget to £300 (I know, it's a 50% budget increase...), then I would recommend the
Acer XZ271Q. But, if you want to keep the budget, then I would recommend the
Samsung C27F390.